Best Pick
eBayeBay Brand Central
10" x 12.5" Polyjacket/Polymailer — 400 Envelopes
10″ × 12.5″ × 0″
+$12.40 USPS Ground Advantage · 3 lb billed
$0.19
each
$0.221 landed
pack of 400 · $76.00
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Cheapest 12×6×4 padded mailer
Compare real eBay prices for 12×6×4 shipping boxes with DIM-weight-aware shipping estimates.
Live listings — sorted by landed cost per box
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eBayeBay Brand Central
12" x 15" Polyjacket/Polymailer — 400 Envelopes
12″ × 15″ × 0″
+$12.40 USPS Ground Advantage · 3 lb billed
$0.23
each
$0.261 landed
pack of 400 · $92.00
eBayeBay Brand Central
14.5" x 18.5" Polyjacket/Polymailer — 400 Envelopes
14.5″ × 18.5″ × 0″
+$12.40 USPS Ground Advantage · 3 lb billed
$0.29
each
$0.321 landed
pack of 400 · $116.00
eBay
PackageZoom #1 Padded Envelopes Bubble Mailer Shipping 7.25 x 12 100 Pack Kraft
7.25″ × 12″ × 0″
+$12.40 USPS Ground Advantage · 3 lb billed
$0.25
each
$0.374 landed
pack of 100 · $25.00
eBayeBay Brand Central
9.5" x 13.25" Padded Bubble Mailer Envelope — 200 Envelopes
9.5″ × 13.25″ × 0″
+$12.40 USPS Ground Advantage · 3 lb billed
$0.45
each
$0.512 landed
pack of 200 · $90.00
eBay
100 12x6x4 Cardboard Paper Boxes Mailing Packing Shipping Box Corrugated Carton
12″ × 6″ × 4″
+$12.40 USPS Ground Advantage · 3 lb billed
$0.60
each
$0.724 landed
pack of 100 · $60.00
Showing 6 of 53 real listings. Want all of them with custom quantity and weight? Search now →
What fits in a 12×6×4 box
A 12 × 6 × 4 inch box holds 288 cubic inches (0.17 cu ft) of interior space, putting it in the medium-category. It's a popular choice for shipping items like hardcover books, shoes, small electronics — things that fit comfortably within those dimensions while leaving room for protective padding. Bulk packs of 25, 50, and 100 are the common listing sizes, with per-unit pricing typically between $0.60 and $2.00 depending on quantity and seller.
Shipping math for this size
Shipping cost for this size depends heavily on dimensional weight. For a 12×6×4 box, UPS and FedEx Ground compute a DIM weight of 3 lbs using their 139 divisor, while USPS Ground Advantage uses a 166 divisor, giving 2 lbs. Carriers bill whichever is greater — your actual weight or the DIM weight. USPS's higher divisor makes it roughly 1 lbs cheaper than UPS/FedEx for this size when your item is light, which is why our search results factor in DIM-weight automatically instead of just showing sticker prices.
How to pick the right pack size
When buying a 12×6×4 box, the biggest cost lever isn't which retailer you pick — it's which pack size you commit to. A 100-pack typically costs 2-3× more than a 25-pack but brings the per-unit cost down by 40-60%. Our ranking is based on *cost per useful box*, which gives bonus boxes partial credit — so a 100-pack can still win for single-box needs if the per-unit price is low enough, but a 25-pack often ranks higher when you only need a few. Every listing below links to a real eBay product page; we don't show placeholder results.
Search with your own dimensions
Pre-filled with 12×6×4. Adjust weight, quantity, or size as needed — we'll re-rank for your exact scenario.